Java - Jframe 不显示按钮标签或文本字段

Question

我是java新手，但是当我尝试创建一个新框架时，我得到的只是一个打开的带有白色背景的新窗口，并且没有添加任何按钮、文本框或标签。我不知道我做错了什么？

private static void MainGui(){

    MainInterfaces MainGui = new MainInterfaces();

    MainGui.setTitle(name+ "'s Inbox");
    MainGui.setSize(600,600);
    MainGui.setVisible(true);
    MainGui.setDefaultCloseOperation(EXIT_ON_CLOSE);
}

主接口(interface)类

class MainInterfaces extends JFrame implements ActionListener
{

    private JButton send;
    private JTextField to, subject, message;
    private JLabel toLbl, subjectLbl, messageLbl;


    public MainInterfaces() { 

        setLayout(new FlowLayout());
        toLbl = new JLabel("Recipient: ");
        subjectLbl = new JLabel("Subject: ");
        messageLbl = new JLabel("Message: ");

        to = new JTextField(32);
        subject = new JTextField(32);
        message = new JTextField(32);

        send = new JButton("SEND");

        add(toLbl);
        add(to);
        add(subjectLbl);
        add(subject);
        add(messageLbl);
        add(message);
        add(send);

    }

    public void actionPerformed(ActionEvent e)
    {
        // TODO Auto-generated method stub

    }
}

Answer 1

您的代码无法编译，因为您有很多错误(您没有 main 方法，private static void MainGui(){ 没有任何意义等) 。请尝试使用此代码，它可以很好地编译并打开 GUI，显示您想要的所有内容(按钮、标签等):

1) 类MainGui.java

class MainGui{
    public static void main(String[] args) {

        MainInterfaces MainGui = new MainInterfaces();

        MainGui.setTitle("'s Inbox");
        MainGui.setSize(600,600);
        MainGui.setVisible(true);
        MainGui.setDefaultCloseOperation(MainGui.EXIT_ON_CLOSE);
    }
}

2)类MainInterfaces.java

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class MainInterfaces extends JFrame implements ActionListener
{

    private JButton send;
    private JTextField to, subject, message;
    private JLabel toLbl, subjectLbl, messageLbl;


    public MainInterfaces() { 



        setLayout(new FlowLayout());
        toLbl = new JLabel("Recipient: ");
        subjectLbl = new JLabel("Subject: ");
        messageLbl = new JLabel("Message: ");

        to = new JTextField(32);
        subject = new JTextField(32);
        message = new JTextField(32);

        send = new JButton("SEND");

        add(toLbl);
        add(to);
        add(subjectLbl);
        add(subject);
        add(messageLbl);
        add(message);
        add(send);




    }

    public void actionPerformed(ActionEvent e)
    {
        // TODO Auto-generated method stub

    }
}